At least in Canadian cities, both bylaw officers and police can enforce these things. Bylaw officers tend to have less discretion on doing their job (and uhhh, fewer other crimes to claim to be busy with)

Though sometimes this double-responsibility just means finger-pointing instead of action.

I've never heard of bylaw officers being a thing in the US. There are some code enforcement people in the US, but they mostly deal in very specific areas (fire code, building code, etc).

Don’t worry, you’re not missing out. Ours are ineffective/unwilling to enforce noise bylaws against vehicles anyway.

This is true. Although, there have been sporadic recent creations of community safety teams and units that deal specifically with the unhoused populations or mentally ill people, as a result of the Black Lives Matter movement.

Who is going to enforce these rules other than cops?

I mean yeah if they never get complains about a given area and they get one call about a loud car driving they're not going to come in lights and sirens to search for them. But if they consistently get complaints it will absolutely guide their decision-making around where to patrol, how often, etc.

Of course this assumes that the political leadership in your municipality hasn't decided that cops don't need to enforce laws (rare outside of a few large cities) and they're not busier with much more serious crimes, underfunded and understaffed, and just not able to spend time on noise complaints (rare but a common talking point).

These rules are usually used as probable cause to target someone the police officer was already targeting. "Profiling" is the better word for it maybe.

If I chop the muffler off my car and run around revving the hell out of my engine I’m not going to say I was targeted or profiled after I’m pulled over in the vehicle that’s calling out to nearby police to take notice of me, regardless of what I’m ticketed for in the end. The squeaky wheel gets the grease as they say. You don’t want to be “targeted” or “profiled” (which isn’t what that would be anyway), then you need to blend.